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Sunday, 27 April 2014

Surgery for shoulder impingement

When you raise your arm, the top of your humerus, where the
rotator cuff tendons attach, “impinge” against your acromion. When this hurts,
it is called impingement syndrome. “Decompressing” the joint by taking some
bone off the acromion (an "acromioplasty”) makes sense, and seems to work well.
The operation has been around for a long time, and there have been many studies
looking at different ways of doing this operation, but very few studies looking
at whether or not it works better than not operating. Interestingly, all of the
studies that have been done conclude that
this operation adds nothing.

I did a lot of these operations in my training and got quite
good at it. When I later saw patients with impingement, I knew what to do -
operate. Fortunately for me, there were no randomised trials on acromioplasty
when I started practice (in the mid-90s) so I could carry on doing what
everyone else was doing. Fortunately for the patients, somebody questioned the
role of acromioplasty and did the studies needed to determine the relative effectiveness
of the procedure.

The role of acromioplasty for patients with impingement (with
or without a rotator cuff tear) was examined in a Cochrane
review published in 2008, covering the literature up to March 2006. Of the
14 trials included, 3 specifically compared acromioplasty to non-operative
treatment in patients with impingement and 1 trial looked at the effect of
adding acromioplasty to surgical repair of a rotator cuff tear. There was no
significant improvement in pain relief or shoulder function from acromioplasty in any of the studies.
Some patients randomised to non-operative treatment ended up undergoing surgery
because of poor results, but (when reported) they had poor results with surgery
too.

It should be noted that one study used a placebo group, and
that the placebo group did not do as well as the non-operative (physiotherapy) or
operative groups, but the placebo group involved placebo physiotherapy, not
placebo surgery.

Also of note, is the observation that it didn’t matter much
how the surgery was performed (open versus arthroscopic).

What about studies that have been published since this
review?

This
study from 2007 looked at adding an acromioplasty to surgical repair of the
rotator cuff and found no significant benefit from the acromioplasty.

This relatively large study with good follow
up found no advantage in adding an acromioplasty to an exercise program for
impingement syndrome. Ditto for the 5-year results
from the same study.

This
study from 2009 asked a different question: how does acromioplasty compare
to simple excision of the subacromial bursa (a usual part of any
‘decompression’ procedure). A good question – maybe it is the bursa that causes
the pain, so just removing that might work? The results were similar in the
two groups. There was no non-operative group to compare to.

This
study will ask another question: does repairing the torn rotator cuff (a
much more common and widely accepted procedure) lead to better results than
non-operative treatment? but this study is still ongoing.

I should note that although the studies are unanimous in
their finding that there is no advantage in performing an acromioplasty, there
was usually a small benefit in the acromioplasty group compared to the non-operative group, just not a statistically
significant benefit (i.e., the difference observed may have been due to chance).
Because of differences in the studies, the authors of the Cochrane
review couldn’t combine the results (meta-analysis). It should also be noted
that the methodology in these studies in generally low, meaning that there is a
risk of bias, which usually favours the intervention. So we don’t know if the
small benefits seen were due to a real advantage of acromioplasty, due to
chance, or due to bias.

The bottom line

All of the studies that have compared acromioplasty to any
alternative, with or without a rotator cuff tear, have not been able to show a significant benefit from the procedure. I think it is time to stop studying acromioplasty because
it is very unlikely to show a significant benefit.

It might also be time to stop performing acromioplasty,
because although these studies have been coming out since the 1990s, the rate
of acromioplasty doesn’t seem to be going down, at least not according to this
Medicare Australia data (link here)
(which only covers private patients, of all ages – different to the US version
of Medicare).

2 comments:

Hi Dr Skeptic, you might like these 2 articles to support your post: http://annals.org/article.aspx?articleid=745977 and http://www.ncbi.nlm.nih.gov/pubmed/24395315 (this one has yet to be rated on PEDro http://www.pedro.org.au/ but appears to be a 8/10 so far - missing out on blinding of subjects and therapists).

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About this blog

This blog explores the true effectiveness of medical interventions, established through scientific study, as opposed to the perceived effectiveness. This highlights our overestimation of the benefits and underestimation of the harms from these interventions.

About Me

I am an academic surgeon with an interest in the scientific evidence for the true effectiveness of medical practice, as opposed to the perceived effectiveness. My aim is to increase the use of science in medical practice.

Why be skeptical about medicine?

Doctors and skeptics are often critical of alternative medicine and other non-medical healing practices because they are not well supported by scientific evidence. This is appropriate.What is inappropriate is the acceptance of medical practices (established and new) without a requirement for the same level of scientific support.The evidence supporting many medical practices is less than many people suppose, and similarly, the harms from medicine are often under-appreciated.We need to ask the same question of medicine that we would ask the alternative practitioner: what is the evidence? But we need skills to be able to critically appraise that evidence, because unlike (say) homeopathy, medical evidence is based on science. This is part of the problem because for many, being scientifically based is reason enough for a treatment to be accepted as true; assuming that a medical treatment works is our default position. This, and the other biases that creep into medical science on so many levels, at least partly due to our keenness to see it work, are the reasons for looking at medicine with a skeptical eye.